Fuel cell system

A fuel cell system, comprising:

• a steam generator configured to heat water to generate steam;
• a reformer configured to cause a reaction between the steam and hydrocarbon to generate a reformed gas containing hydrogen;
• a fuel cell stack, which has an anode and a cathode, and is configured to generate electric energy through an electrochemical reaction caused between the reformed gas supplied to the anode and an oxidant supplied to the cathode;
• and
• an ejector configured to supply at least one of a raw material containing the hydrocarbon or an anode circulating gas obtained by recovering a part of an anode exhaust gas discharged from the anode, to the reformer by using the steam as a driving fluid,
• wherein the steam generator includes:
• an evaporation flow passage through which the water flows;
• an anode exhaust gas flow passage that is thermally connected to the evaporation flow passage and through which the anode exhaust gas flows;
• and
• an auxiliary heating device configured to heat the water,
• wherein the anode exhaust gas flow passage and the auxiliary heating device are opposed to each other across the evaporation flow passage,
• wherein the anode exhaust gas flow passage extends in an up-and-down direction,
• wherein the steam generator includes:
• a flow passage wall that extends in the up-and-down direction and defines the anode exhaust gas flow passage;
• an inflow pipe that penetrates the flow passage wall and is connected to the anode exhaust gas flow passage and into which the anode exhaust gas flows;
• and
• an outflow pipe that is connected to the anode exhaust gas flow passage at a position above the inflow pipe and from which the anode exhaust gas flows out, and
• wherein a dew condensation water storage space configured to store dew condensation water is defined below the inflow pipe in the anode exhaust gas flow passage.

A fuel cell system, comprising:

• a steam generator configured to heat water to generate steam;
• a reformer configured to cause a reaction between the steam and hydrocarbon to generate a reformed gas containing hydrogen;
• a fuel cell stack, which has an anode and a cathode, and is configured to generate electric energy through an electrochemical reaction caused between the reformed gas supplied to the anode and an oxidant supplied to the cathode;
• an ejector configured to supply at least one of a raw material containing the hydrocarbon or an anode circulating gas obtained by recovering a part of an anode exhaust gas discharged from the anode, to the reformer by using the steam as a driving fluid;
• a stack temperature sensor configured to detect a temperature of the fuel cell stack;
• a water separator configured to separate the anode exhaust gas into condensate water and an anode recovered gas;
• a recovery branch portion configured to split the anode recovered gas into a recycled combustion gas to be supplied to a combustor that is thermally connected to the reformer, and the anode circulating gas;
• an interrupting valve configured to interrupt supply of the recycled combustion gas to the combustor;
• and
• a controller,
• wherein the steam generator includes:
• an evaporation flow passage through which the water flows;
• an anode exhaust gas flow passage that is thermally connected to the evaporation flow passage and through which the anode exhaust gas flows;
• and
• an auxiliary heating device configured to heat the water,
• wherein the anode exhaust gas flow passage and the auxiliary heating device are opposed to each other across the evaporation flow passage,
• wherein, when the fuel cell system is activated, the controller controls the auxiliary heating device so that supply of the steam to the reformer is started within a specific period,
• wherein the specific period is a period after the temperature of the fuel cell stack rises to a first temperature and before the temperature of the fuel cell stack rises to a second temperature that is higher than the first temperature, and
• wherein, when the fuel cell system is stopped, the controller stops generation of the electric energy in the fuel cell stack, closes the interrupting valve, controls the auxiliary heating device to ensure a flow rate of the steam, and decreases a temperature of the reformer and a temperature of the fuel cell stack.